1. Field of the Invention
The present invention relates to apparatus and methods for reducing pollutants in effluent gas flow, particularly exhaust emissions resulting from combustion processes.
2. Background Art
In today's industrial world, the amount of pollution present has reached enormous proportions. Not only do factories, buses, cars, trucks, stationary combustion engines, and commercial and industrial processes provide air pollution but, additionally, migration of releases from dump sites, land fills, sewage treatment lagoons, waste heaps, etc. are sources of air contamination.
In order to understand the structure and theory of the apparatus and system of the present invention, a brief statement on the area of pollution is necessary.
As emission and environmental regulations become increasingly more stringent, waste treatment, hazardous chemicals and combustion products, in general, must be handled with innovative methods to reduce their impact upon the environment and upon society. To ultimately be successful, the method employed to resolve the problems must be economical, highly efficient in the reduction of emissions with respect to the equipment it serves, and available for widespread use.
Air pollution chemistry is a complex issue. Many different sources have created emission reaction in quantum proportions. The carbon/oxygen/nitrogen cycles interplay in all aspects of organic and inorganic life and in all chemical reactions. These cycles have photochemical reactions (vibrational reaction due to light absorption), as well as physical vibrational reactions due to the interplay of excited electrons from electrochemical interactions. It is in these three cycles, as illustrated by natural processes, that air pollution chemistry finds its effectiveness and explanations.
In the 1960's, it was recognized that the hydroxyl radical is, with several important exceptions, the key reactive intermediate in the photo-oxidation of most inorganic and many organic compounds found in polluted atmospheres. The NO3 and the HOHO radicals also play important roles in the atmosphere. The primary air pollutants are NO, NO2, SO2, CO2, and hydrocarbons. Devices which reduce the entrance of these compounds into the atmosphere and which are efficient and inexpensive are desired.
A variety of devices and the methods for removing pollutants from effluent gas flows are available today. Such devices and methods focus on the use of mechanical, electrical, electro-mechanical, and chemical processes. Typical examples of such prior art methods include filters, aqueous scrubbers, electrostatic precipitators, catalytic converters.
One type of prior art pollution control device which utilizes electrical means generally teaches the reduction of pollutants to a particulate or mist form through precipitation. In these devices, effluent gas may be passed through an electric current whereby particles become charged. These charged particles drop out of the gas and are collected. One problem with these precipitation devices is the dilemma of subsequent handling of the collected pollutant particles. Once they are collected, the pollutant particles must still be somehow discarded or stored.
A number of prior art variations on this technology deal primarily with methods of electrostatic precipitation to maximize precipitation efficiency or to minimize the number of cleansing cycles required of the electrostatic precipitator. These variations are aimed towards minimizing the down time of the electrostatic precipitator. However, the problem remains of storage or elimination of the collected pollutant particles once they are separated from the gases.
Such prior art processes and apparatus are typified by the following patents: U.S. Pat. No. 2,382,253, issued to Penney, et al. on Aug. 14, 1945; U.S. Pat. No. 3,706,182, issued to Sargent on Dec. 19, 1972; U.S. Pat. No. 3,739,554, issued to Whetten, et al. on Jun. 19, 1973; U.S. Pat. No. 3,869,362 issued to Machi, et al. on Mar. 4, 1975 and U.S. Pat. No. 3,907,520 issued to Huang, et al. on Sep. 23, 1975.